While slaughtering a normal animal
بِسْمِ اللہِ وَاللہُ أَکْبَرُ [اَللّٰہُمَّ مِنْکَ وَ لَکَ] اَللّٰہُمَّ تَقَبَّلْ مِنِّيْ
In the Name of Allah, Allah is the Greatest! [O Allah, from You and to You.] O Allah, accept it from me.
References
[Sahih Muslim - 1966,1967]